<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    // 打印100以内的所偶数 的 和
    var num = 0 //定义一个变量来存放总数和
    for(var i = 0; i <= 100; i++){
        if(i % 2 == 0){ //求偶数
            num += i
        }
    }
    console.log(num)
</script>
</html>